1103824: Add a catchall excepthook for rhsmd

To avoid ever having rhsmd having uncaught exceptions.
Am I correct that stderr here does not go to syslog but does generate a cron problem or email.

Personally I think we need to avoid writing to stderr, but add something like:

log_syslog("Error checking subscription status, see /var/log/rhsm/rhsm.log for more details.")

It makes sense to me to keep cron quiet and happy, log simple indicator something went wrong in syslog, and full trace in rhsm.log.

What do you think?